[yoda-svn] r306 - in trunk: . include/YODA src

[blackhole at projects.hepforge.org]

Author: buckley
Date: Mon Aug 22 10:11:09 2011
New Revision: 306

Log:
Remove use of sign(weight) in filling sum(w2) -- I think this was an historical attempt based on a scaling axiom which turned out to be inappropriate. Also adding a LowStatsError throw for attempting to calculate the mean of an unfilled distribution.

Modified:
   trunk/ChangeLog
   trunk/TODO
   trunk/include/YODA/Dbn1D.h
   trunk/src/Dbn1D.cc

Modified: trunk/ChangeLog
==============================================================================
--- trunk/ChangeLog	Mon Aug 22 09:56:10 2011	(r305)
+++ trunk/ChangeLog	Mon Aug 22 10:11:09 2011	(r306)
@@ -1,5 +1,9 @@
 2011-08-22  Andy Buckley  <andy at insectnation.org>
 
+	* Remove use of sign(weight) in filling sum(w2) -- I think this
+	was an historical attempt based on a scaling axiom which turned
+	out to be inappropriate.
+
 	* Reworking the Bin1D inheritance and composition design so that
 	all bin types store a single distribution object -- a Dbn1D for
 	histo bins and a Dbn2D for profile bins.

Modified: trunk/TODO
==============================================================================
--- trunk/TODO	Mon Aug 22 09:56:10 2011	(r305)
+++ trunk/TODO	Mon Aug 22 10:11:09 2011	(r306)
@@ -15,8 +15,7 @@
 
 * Rework Axis1D to operate as Axis2D does (MICHAL)
 
-* Throw LowStatsError for errors and profile histo points with no fills -- any
-  explicit action needed? (AB)
+* Template Bin2D and HistoBin2D on DBN type (Dbn2D/3D) cf. Bin1D<DBN>
 
 * Rebinning: global rebinning by integer factor(s) (AB for 1D, MICHAL for 2D)
   Different rebinning factors for X and Y in 2D. Implement for 1D first,

Modified: trunk/include/YODA/Dbn1D.h
==============================================================================
--- trunk/include/YODA/Dbn1D.h	Mon Aug 22 09:56:10 2011	(r305)
+++ trunk/include/YODA/Dbn1D.h	Mon Aug 22 10:11:09 2011	(r306)
@@ -34,7 +34,9 @@
       reset();
     }
 
+
     /// @brief Constructor to set a distribution with a pre-filled state.
+    ///
     /// Principally designed for internal persistency use.
     Dbn1D(unsigned int numEntries, double sumW, double sumW2, double sumWX, double sumWX2) {
       _numFills = numEntries;
@@ -57,6 +59,7 @@
     /// @todo Be careful about negative weights.
     void fill(double val, double weight=1.0);
 
+
     /// Reset the internal counters.
     void reset() {
       _numFills = 0;
@@ -66,6 +69,7 @@
       _sumWX2 = 0;
     }
 
+
     /// Rescale as if all fill weights had been different by factor @a scalefactor.
     void scaleW(double scalefactor) {
       const double sf = scalefactor;
@@ -76,6 +80,7 @@
       _sumWX2 *= sf2;
     }
 
+
     /// Rescale x: needed if histo bin edges are rescaled.
     void scaleX(double factor) {
       _sumWX *= factor;
@@ -105,10 +110,7 @@
     //@{
 
     /// Weighted mean, \f$ \bar{x} \f$, of distribution.
-    double mean() const {
-      // This is ok, even for negative sum(w)
-      return _sumWX/_sumW;
-    }
+    double mean() const;
     /// Synonym for interface compatibility with Dbn2D
     double xMean() const { return mean(); }
 
@@ -126,6 +128,7 @@
     /// Synonym for interface compatibility with Dbn2D
     double xStdDev() const { return stdDev(); }
 
+
     /// Weighted standard error on the mean, \f$ \sim \sigma/\sqrt{N-1} \f$, of distribution.
     double stdErr() const;
     /// Synonym for interface compatibility with Dbn2D

Modified: trunk/src/Dbn1D.cc
==============================================================================
--- trunk/src/Dbn1D.cc	Mon Aug 22 09:56:10 2011	(r305)
+++ trunk/src/Dbn1D.cc	Mon Aug 22 10:11:09 2011	(r306)
@@ -4,6 +4,7 @@
 // Copyright (C) 2008-2011 The YODA collaboration (see AUTHORS for details)
 //
 #include "YODA/Dbn1D.h"
+#include "YODA/Utils/MathUtils.h"
 
 namespace YODA {
 
@@ -11,22 +12,29 @@
   void Dbn1D::fill(double val, double weight) {
     _numFills += 1;
     _sumW += weight;
-    double w2 = weight*weight;
-    /// @todo Correct?
-    if (weight < 0) w2 *= -1;
-    _sumW2 += w2;
+    //const double w2 = sign(weight) * weight*weight;
+    _sumW2 += weight*weight;
     _sumWX += weight*val;
     _sumWX2 += weight*val*val;
   }
 
 
+  double Dbn1D::mean() const {
+    if (isZero(effNumEntries(), 0.0)) {
+      throw LowStatsError("Requested mean of a distribution with no net fill weights");
+    }
+    // This is ok, even for negative sum(w)
+    return _sumWX/_sumW;
+  }
+
+
   double Dbn1D::variance() const {
     // Weighted variance defined as
     // sig2 = ( sum(wx**2) * sum(w) - sum(wx)**2 ) / ( sum(w)**2 - sum(w**2) )
     // see http://en.wikipedia.org/wiki/Weighted_mean
-    if (effNumEntries() == 0.0) {
+    if (isZero(effNumEntries(), 0.0)) {
       throw LowStatsError("Requested width of a distribution with no net fill weights");
-    } else if (effNumEntries() <= 1.0) {
+    } else if (fuzzyLessEquals(effNumEntries(), 1.0)) {
       throw LowStatsError("Requested width of a distribution with only one effective entry");
     }
     const double num = _sumWX2*_sumW - _sumWX*_sumWX;
@@ -64,7 +72,7 @@
 
 
   Dbn1D& Dbn1D::subtract(const Dbn1D& d) {
-    _numFills += d._numFills; //< @todo Hmm, what's best?!?
+    _numFills += d._numFills; //< @todo Hmm, add or subtract?!?
     _sumW     -= d._sumW;
     _sumW2    -= d._sumW2;
     _sumWX    -= d._sumWX;